It is known for charging systems in plug-in electric vehicles to include some custom charging features. For example, some charging systems allow a user to provide electricity rate preferences so that the vehicle can be charged during off-peak times when demand for electricity is lower and so is the associated cost. The cost of electricity, however, is not the only concern or factor that should be taken into account when devising a charging scheme for a plug-in electric vehicle.
Another factor that should be considered relates to the life or health of the battery. Generally speaking, the longer a high voltage battery, like those based on lithium-ion chemistries, is at an elevated state-of-charge (SOC), the more potential there is for battery life degradation. The dual objectives of reducing electricity costs and preserving battery life are not always synchronous with one another. For example, it may be less expensive to charge the vehicle as soon as the user plugs it in to an external power source, but this could result in a high SOC level for many hours before the vehicle is driven and could have a diminishing effect on battery life. Conversely, if the vehicle battery is only charged during the period immediately preceding a scheduled departure time in an effort to reduce the duration at which the vehicle battery is at a high SOC, with no regard to electricity cost, then this could result in unacceptably high electricity costs.
Therefore, it would be beneficial to find a balanced approach to charging plug-in electric vehicles that considers both electricity costs and battery life, among other factors.